Neutrino factory for both large and small ${\theta }_{13}$

An analysis of the neutrino oscillation physics capability of a low-energy neutrino factory is presented, including a first simulation of the detector efficiency and event energy threshold. The sensitivity of the physics reach to the presence of backgrounds is also studied. We consider a representative baseline of 1480 km, we use muons with 4.12 GeV energy and we exploit a very conservative estimate of the energy resolution of the detector. Our analysis suggests an impressive physics reach for this setup, which can eliminate degenerate solutions, for both large and small values of the mixing angle ${\theta }_{13}$, and can determine leptonic $CP$ violation and the neutrino mass hierarchy with extraordinary sensitivity.

Figure 1

Diagram of superconducting transmission line design.

Figure 2

Schematic of totally active scintillator detector.

Figure 3

Momentum resolution as a function of the muon momentum.

Figure 4

(a) Efficiency for reconstructing positive muons. (b) Muon charge misidentification rate as a function of the initial muon momentum.

Figure 5

(a) Reconstruction efficiency of ${\nu }_{\mu }$ CC events as a function of neutrino interaction energy. (b) Fraction of ${\nu }_{\mu }$ CC events with a reconstructed muon.

Figure 6

68%, 90% and 95% (2 dof) C.L. contours resulting from the fits at $L=1480\mathrm{km}$ assuming two central values for ${sin}^2{\theta }_{23}=0.4$ and 0.44 and $\Delta m_{31}^2=2.5\times {10}^{-3}{\mathrm{eV}}^2$. In the left (right) panel, ${\theta }_{13}=8°$ (3°). The statistics considered for both simulations corresponds to $1\times {10}^{23}\mathrm{kton}\mathrm{decays}$. Only disappearance data have been used to perform these plots.

Figure 7

68%, 90% and 95% (2 dof) C.L. contours resulting from the fits at $L=1480\mathrm{km}$ assuming four central values for $\delta =0°$, 90°, $-90°$ and 180° and ${\theta }_{13}=2°$ without backgrounds (left panel) and with a background level of ${10}^{-3}$ (right panel). The additional ${\theta }_{23}$ octant solutions are depicted by dotted lines. The statistics considered for both simulations corresponds to ${10}^{23}\mathrm{kton}\mathrm{decays}$.

Figure 8

68%, 90% and 95% (2 dof) C.L. contours resulting from the fits at $L=1480\mathrm{km}$ assuming four central values for $\delta =0°$, 90°, $-90°$ and 180° and ${\theta }_{13}=1°$ without backgrounds (left panel) and with a background level of ${10}^{-3}$ (right panel). The statistics considered for both simulations correspond to $3\times {10}^{23}\mathrm{kton}\mathrm{decays}$.

Figure 9

95% C.L. (1 dof) hierarchy resolution assuming that the far detector is located at a distance of 1480 km at the Henderson mine. The solid (dotted) curves depict the results assuming $1\times {10}^{23}\mathrm{kton}\mathrm{decays}$ ($3\times {10}^{23}\mathrm{kton}\mathrm{decays}$) without backgrounds. The long-dashed (short-dashed) black curves depict the results assuming $1\times {10}^{23}\mathrm{kton}\mathrm{decays}$ ($3\times {10}^{23}\mathrm{kton}\mathrm{decays}$) with a background level of ${10}^{-3}$.

Figure 10

95% C.L. (1  dof) $CP$ violation extraction assuming that the far detector is located at a distance of 1480. The solid (dotted) curves depict the results assuming $1\times {10}^{23}\mathrm{kton}\mathrm{decays}$ ($3\times {10}^{23}\mathrm{kton}\mathrm{decays}$) without backgrounds. The long-dashed (short-dashed) black curves depict the results assuming $1\times {10}^{23}\mathrm{kton}\mathrm{decays}$ ($3\times {10}^{23}\mathrm{kton}\mathrm{decays}$) with a background level of ${10}^{-3}$.

Figure 11

Simulation results for magnetic cavern design.

Figure 12

STL solenoid magnetic cavern field uniformity in the $X\mathrm{\text{−}}Z$ plane.

Figure 13

On-axis $B$ field in $T$ as a function of position along the $z$ axis (m).